[PATCH AUTOSEL 5.4 10/73] net: dsa: mv88e6xxx: fix lockup on warm boot

[Sasha Levin]

From: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>

[ Upstream commit 0395823b8d9a4d87bd1bf74359123461c2ae801b ]

If the switch is not hardware reset on a warm boot, interrupts can be
left enabled, and possibly pending. This will cause us to enter an
infinite loop trying to service an interrupt we are unable to handle,
thereby preventing the kernel from booting.

Ensure that the global 2 interrupt sources are disabled before we claim
the parent interrupt.

Observed on the ZII development revision B and C platforms with
reworked serdes support, and using reboot -f to reboot the platform.

Fixes: dc30c35be720 ("net: dsa: mv88e6xxx: Implement interrupt support.")
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
Reviewed-by: Andrew Lunn <andrew@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/dsa/mv88e6xxx/global2.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/mv88e6xxx/global2.c b/drivers/net/dsa/mv88e6xxx/global2.c
index bdbb72fc20ede..6240976679e1e 100644
--- a/drivers/net/dsa/mv88e6xxx/global2.c
+++ b/drivers/net/dsa/mv88e6xxx/global2.c
@@ -1083,6 +1083,13 @@ int mv88e6xxx_g2_irq_setup(struct mv88e6xxx_chip *chip)
 {
 	int err, irq, virq;
 
+	chip->g2_irq.masked = ~0;
+	mv88e6xxx_reg_lock(chip);
+	err = mv88e6xxx_g2_int_mask(chip, ~chip->g2_irq.masked);
+	mv88e6xxx_reg_unlock(chip);
+	if (err)
+		return err;
+
 	chip->g2_irq.domain = irq_domain_add_simple(
 		chip->dev->of_node, 16, 0, &mv88e6xxx_g2_irq_domain_ops, chip);
 	if (!chip->g2_irq.domain)
@@ -1092,7 +1099,6 @@ int mv88e6xxx_g2_irq_setup(struct mv88e6xxx_chip *chip)
 		irq_create_mapping(chip->g2_irq.domain, irq);
 
 	chip->g2_irq.chip = mv88e6xxx_g2_irq_chip;
-	chip->g2_irq.masked = ~0;
 
 	chip->device_irq = irq_find_mapping(chip->g1_irq.domain,
 					    MV88E6XXX_G1_STS_IRQ_DEVICE);
-- 
2.20.1